Voltage regulators may be used, for example, to provide different supply voltage signals to different portions of an integrated circuit. A voltage regulator may, for example, receive a supply voltage signal from a power supply external to the integrated circuit and convert the supply voltage signal into a lower supply voltage signal for use by a portion of the integrated circuit. Designing portions of an integrated circuit to operate using lower supply voltage signals helps reduce power consumption of the integrated circuit.
Some prior linear voltage regulators use an analog output stage to output a supply voltage signal to a load on an integrated circuit. Such a regulator modulates an analog voltage signal input to the gate of driver transistor(s) to help maintain a relatively steady voltage level of the supply voltage signal as the load varies. A required current efficiency of the regulator, however, limits the speed at which the regulator may respond to load variations. As one example, a regulator may have only 10 milliamperes (mA) of quiescent current available to output up to 1 ampere (A) of current. Because the driver transistor(s) of the regulator are sized to deliver the maximum output current, or 1 A in this example, and are therefore relatively large, the speed at which the regulator responds to load variations can be relatively slow. Modulating the input analog voltage signal using an analog buffer may also draw available quiescent current a substantial amount of the time the regulator is operating.